There are a wide variety of apparatus or devices which use internal springs that are required to have a particular preload or spring setting. This is particularly true in the aerospace industry for such devices as torque limiters, clutches, brakes and the like. Such devices may include friction plates, ball-ramp mechanisms and the like which require preloading.
It is advantageous to control the preloading force of the spring within a small tolerance range or band. Otherwise, some of the components of the device have to be oversized to accommodate the upper limits of the tolerance range. Attempts have been made to alleviate this problem by providing a spring cartridge which contains the spring and preloading the spring within the cartridge externally of the housing and at a given preload or spring setting. The cartridge then is assembled within the housing presumably to maintain the given preload during use of the device. However, because of deflections of the housing itself and other internal components, it is difficult to predict what the preload level actually is once the cartridge is positioned in the housing.
This invention is directed to solving the above dilemma and satisfying a need for preloading an internal spring to a narrow preload tolerance range or band notwithstanding induced deflections occurring in components surrounding and/or mounting the spring internally.